A blog for better streets and public spaces in Portland, Maine.

Tuesday, November 23, 2010

True Confessions of a Recovering Traffic Engineer

Via Portland Bike/Ped Committee member and Bike Commuting Meetup founder John Brooking, here's an excerpt from an essay written by a recovering traffic engineer:

After graduating from college with a civil engineering degree, I found myself working in my home town for a local engineering firm doing mostly municipal engineering (roads, sewer pipe, water pipe, stormwater). A fair percentage of my time was spent convincing people that, when it came to their road, I knew more than they did.

When people would tell me that they did not want a wider street, I would tell them that they had to have it for safety reasons.

When they answered that a wider street would make people drive faster and that would be seem to be less safe, especially in front of their house where their kids were playing, I would confidently tell them that the wider road was more safe, especially when combined with the other safety enhancements the standards called for.

When people objected to those other "enhancements", like removing all of the trees near the road, I told them that for safety reasons we needed to improve the sight distances and ensure that the recovery zone was free of obstacles.

When they pointed out that the "recovery zone" was also their "yard" and that their kids played kickball and hopscotch there, I recommended that they put up a fence, so long as the fence was outside of the right-of-way.

When they objected to the cost of the wider, faster, treeless road that would turn their peaceful, front yard into the viewing area for a drag strip unless they built a concrete barricade along their front property line, I informed them that progress was sometimes expensive, but these standards have been shown to work across the state, the country and the world and I could not compromise with their safety.

In retrospect I understand that this was utter insanity. Wider, faster, treeless roads not only ruin our public places, they kill people. Taking highway standards and applying them to urban and suburban streets, and even county roads, costs us thousands of lives every year. There is no earthly reason why an engineer would ever design a fourteen foot lane for a city block, yet we do it continuously. Why?

The answer is utterly shameful: Because that is the standard.

These "standards," it turns out, not only lack a rigorous theoretical underpinning - they're also based on flawed values. The author also writes:
An engineer designing a street or road prioritizes the world in this way, no matter how they are instructed:
  1. Traffic speed
  2. Traffic volume
  3. Safety
  4. Cost
The rest of the world generally would prioritize things differently, as follows:
  1. Safety
  2. Cost
  3. Traffic volume
  4. Traffic speed
In other words, the engineer first assumes that all traffic must travel at speed. Given that speed, all roads and streets are then designed to handle a projected volume. Once those parameters are set, only then does an engineer look at mitigating for safety and, finally, how to reduce the overall cost (which at that point is nearly always ridiculously expensive).
This sums up why Augusta just spent several million on a highway widening in downtown Portland that's making traffic worse while it puts pedestrians in danger.

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